PUERTO LAS OLLAS, Mexico -- The Mexican army has carried out forced disappearances, acts of torture and illegal raids in pursuit of drug traffickers, according to documents and interviews with victims, their families, political leaders and human rights monitors.

From the violent border cities where drugs are brought into the United States to the remote highland regions where poppies and marijuana are harvested, residents and human rights groups describe an increasingly brutal war in which the government, led by the army, is using harsh measures to battle the cartels that continue to terrorize much of the country.

In Puerto Las Ollas, a mountain village of 50 people in the southern state of Guerrero, residents recounted how soldiers seeking information last month stuck needles under the fingernails of a disabled 37-year-old farmer, jabbed a knife into the back of his 13-year-old nephew, fired on a pastor, and stole food, milk, clothing and medication.

In Tijuana, across the border from San Diego, two dozen policemen who were arrested on drug charges in March alleged that, to extract confessions, soldiers beat them, held plastic bags over their heads until some lost consciousness, strapped their feet to a ceiling while dunking their heads in water and applied electric shocks, according to court documents, letters and interviews with their relatives and defense lawyers.

The officers were detained at a military base for more than a month.

Mexican officials acknowledged that abuses have occurred in the fight against traffickers but described the cases as isolated. In some instances, drug traffickers may be accusing the army of torture and other human rights violations as propaganda and to deflect attention from the government's efforts to dismantle their operations, the officials said.

"I know that the armed forces are not acting inappropriately, although there have been some cases," said Interior Minister Fernando Gómez Mont, who is responsible for coordinating security operations across Mexico. "The government honestly believes that. There is no incentive for abuse."

Mexican security forces have long had a spotty human rights record, but the growing number of abuse allegations appears to be a direct response to the savagery unleashed by the cartels after President Felipe Calderón put the military in charge of the drug war in December 2006. Most of the violations have occurred in regions where the sight of dismembered bodies of soldiers and police is remarkably common. In the state of Michoacán, investigators with the government's National Human Rights Commission concluded that the army committed abuses against 65 people over three days -- including several cases of torture and the rape of two girls -- after five soldiers were killed in an attack in May 2007.

The U.S. government has encouraged and, in part, funded, Calderón's risky strategy of using the army to fight the cartels that handle 90 percent of all cocaine that enters the United States. U.S. officials said Calderón has initiated reforms that they think ultimately will increase respect for human rights among soldiers and police.

However, U.S. officials warned that the abuse allegations could lead Congress to withhold more than $100 million in anti-narcotics assistance.

The cases in Puerto Las Ollas and Tijuana are under investigation by the National Human Rights Commission, which has been overwhelmed with more than 2,000 complaints about the army -- 140 a month this year. The commission has documented 26 cases of abuse, 17 of which involved torture, including asphyxiation and the application of electric shocks to the genitals of drug suspects.

"What happens is the army takes [suspects] back to their bases -- and of course a military base is not a place to detain people suspected of a crime -- and they begin to ask questions," said Mauricio Ibarra, who oversees investigations for the commission. "And to help them remember or to get information, they use torture."